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id="post-info"><h1 class="post-title">发布订阅</h1><div id="post-meta"><div class="meta-firstline"><span class="post-meta-date"><i class="far fa-calendar-alt fa-fw post-meta-icon"></i><span class="post-meta-label">发表于</span><time class="post-meta-date-created" datetime="2020-04-26T16:00:00.000Z" title="发表于 2020-04-27 00:00:00">2020-04-27</time><span class="post-meta-separator">|</span><i class="fas fa-history fa-fw post-meta-icon"></i><span class="post-meta-label">更新于</span><time class="post-meta-date-updated" datetime="2019-06-03T16:00:00.000Z" title="更新于 2019-06-04 00:00:00">2019-06-04</time></span><span class="post-meta-categories"><span class="post-meta-separator">|</span><i class="fas fa-inbox fa-fw post-meta-icon"></i><a class="post-meta-categories" href="/categories/%E8%AE%BE%E8%AE%A1%E6%A8%A1%E5%BC%8F/">设计模式</a></span></div><div class="meta-secondline"><span class="post-meta-separator">|</span><span class="post-meta-wordcount"><i class="far fa-file-word fa-fw post-meta-icon"></i><span class="post-meta-label">字数总计:</span><span class="word-count">2.5k</span><span class="post-meta-separator">|</span><i class="far fa-clock fa-fw post-meta-icon"></i><span class="post-meta-label">阅读时长:</span><span>9分钟</span></span><span class="post-meta-separator">|</span><span class="post-meta-pv-cv" id="" data-flag-title="发布订阅"><i class="far fa-eye fa-fw post-meta-icon"></i><span class="post-meta-label">阅读量:</span><span id="busuanzi_value_page_pv"></span></span></div></div></div></header><main class="layout" id="content-inner"><div id="post"><article class="post-content" id="article-container"><h1 id="设计模式"><a href="#设计模式" class="headerlink" title="设计模式"></a>设计模式</h1><h2 id="发布订阅设计模式"><a href="#发布订阅设计模式" class="headerlink" title="发布订阅设计模式"></a>发布订阅设计模式</h2><figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line"><span class="number">1.</span> 设计模式是一种思想 为的是更好的管理我们的代码</span><br></pre></td></tr></table></figure>
<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line"><span class="number">1.</span> 比如我现在要给一个Dom 元素 绑定多个 事件</span><br><span class="line"><span class="number">2.</span> 如果使用 DOM <span class="number">0</span> 级别绑定 就显得比较不太方便</span><br><span class="line"><span class="number">3.</span> 使用 DOM2级 去绑定 就有了事件池的概念</span><br><span class="line"><span class="number">4.</span> 但是 以上只支持 我们的浏览器 自己的内置事件 比如 click mouseEnter 之类的 如果我们自己定义的事件就不支持</span><br><span class="line"><span class="number">5.</span> 所以我们基于上述的思想 就可以 自己写个事件池 然后支持自己的自定义事件</span><br></pre></td></tr></table></figure>
<h2 id="DOM-0级"><a href="#DOM-0级" class="headerlink" title="DOM 0级"></a>DOM 0级</h2><figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">fn1</span>(<span class="params"></span>) </span>&#123;<span class="built_in">console</span>.log(<span class="number">1</span>)&#125;</span><br><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">fn2</span>(<span class="params"></span>) </span>&#123;<span class="built_in">console</span>.log(<span class="number">2</span>)&#125;</span><br><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">fn2</span>(<span class="params"></span>) </span>&#123;<span class="built_in">console</span>.log(<span class="number">3</span>)&#125;</span><br><span class="line">box.onclick = <span class="function"><span class="keyword">function</span> (<span class="params"></span>) </span>&#123;</span><br><span class="line">  fn1()</span><br><span class="line">  fn2()</span><br><span class="line">  fn3()</span><br><span class="line">&#125;</span><br><span class="line"><span class="comment">//  以上只是一个简单的例子 假如 我们 这三个方法 都不在一个 js文件里 你就需要分别的引入进来 然后在 我们的click函数里去写入 如果某一天我又增加了很多 所以 你就要不停的去引入文件 然后在我们的事件处理函数里 去填写执行的方法 这样在管理代码层面 我们是低效的</span></span><br></pre></td></tr></table></figure>
<h2 id="DOM-2级"><a href="#DOM-2级" class="headerlink" title="DOM 2级"></a>DOM 2级</h2><figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">fn1</span>(<span class="params"></span>) </span>&#123;<span class="built_in">console</span>.log(<span class="number">1</span>)&#125;</span><br><span class="line">box.addEventListener(<span class="string">&#x27;click&#x27;</span>,fn1)</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">fn2</span>(<span class="params"></span>) </span>&#123;<span class="built_in">console</span>.log(<span class="number">2</span>)&#125;</span><br><span class="line">box.addEventListener(<span class="string">&#x27;click&#x27;</span>,fn2)</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">fn3</span>(<span class="params"></span>) </span>&#123;<span class="built_in">console</span>.log(<span class="number">3</span>)&#125;</span><br><span class="line">box.addEventListener(<span class="string">&#x27;click&#x27;</span>,fn3)</span><br><span class="line"></span><br><span class="line"><span class="comment">//这样 即使 分了很多文件 我们在代码管理层面上也好维护  他会按照你的代码顺序去执行</span></span><br></pre></td></tr></table></figure>
<h2 id="事件池"><a href="#事件池" class="headerlink" title="事件池"></a>事件池</h2><div class="table-container">
<table>
<thead>
<tr>
<th style="text-align:center">元素</th>
<th style="text-align:center">事件类型</th>
<th style="text-align:center">方法</th>
<th style="text-align:center">阶段</th>
</tr>
</thead>
<tbody>
<tr>
<td style="text-align:center">box</td>
<td style="text-align:center">click</td>
<td style="text-align:center">Fn1</td>
<td style="text-align:center">False</td>
</tr>
<tr>
<td style="text-align:center">box</td>
<td style="text-align:center">click</td>
<td style="text-align:center">Fn2</td>
<td style="text-align:center">False</td>
</tr>
</tbody>
</table>
</div>
<h2 id="自定义事件池"><a href="#自定义事件池" class="headerlink" title="自定义事件池"></a>自定义事件池</h2><figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line"><span class="number">1.</span> 首先我们要有一个容器 也就是我们的事件池 </span><br><span class="line"><span class="number">2.</span> 然后会有 on 方法 向事件池中 去加入哪个事件</span><br><span class="line"><span class="number">3.</span> off方法 从事件中移除事件</span><br><span class="line"><span class="number">4.</span> fire方法 通知哪个方法执行</span><br><span class="line"><span class="number">5.</span> 所以我们要创建一个事件池 发布一个计划表 基于 on / off 向事件池中增删方法 订阅计划 / 任务 fire 就是达到条件 通知计划表中的订阅任务的执行</span><br></pre></td></tr></table></figure>
<p><img src="/Users/笔记/笔记/设计模式/1.png" alt="1"></p>
<h2 id="基于单利模式编写事件发布订阅"><a href="#基于单利模式编写事件发布订阅" class="headerlink" title="基于单利模式编写事件发布订阅"></a>基于单利模式编写事件发布订阅</h2><figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line"><span class="number">1.</span> 首先我们要有一个池子 用来存放 我们的事件名称 和 事件名称里面对应的方法</span><br><span class="line"><span class="number">2.</span> 然后我们需要个添加的方法 on 用来 向我们的池子里添加 我们的自定义事件名称 和 对应你事件名称的方法</span><br><span class="line"><span class="number">3.</span> off 用来移除 我们的自定义事件 和对应的方法</span><br><span class="line"><span class="number">4.</span> fire 通知方法 用来 执行我们自定义事件名称 里面 所对应的方法</span><br></pre></td></tr></table></figure>
<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">//基于单例模式实现</span></span><br><span class="line"><span class="keyword">let</span> subscribe = (<span class="function"><span class="keyword">function</span> (<span class="params"></span>) </span>&#123;</span><br><span class="line">    <span class="comment">//1.定义一个池子</span></span><br><span class="line">    <span class="keyword">let</span> pond = &#123;&#125;</span><br><span class="line">    <span class="comment">//2.关于事件池中方法的管理</span></span><br><span class="line">    <span class="comment">/*</span></span><br><span class="line"><span class="comment">    * @params</span></span><br><span class="line"><span class="comment">    * type : 自定义事件的名称</span></span><br><span class="line"><span class="comment">    * func : 你要执行的事件函数</span></span><br><span class="line"><span class="comment">    * params : 执行的时候传递的参数</span></span><br><span class="line"><span class="comment">    */</span></span><br><span class="line">    <span class="keyword">const</span> on = <span class="function"><span class="keyword">function</span> (<span class="params">type,func</span>) </span>&#123;</span><br><span class="line">        <span class="comment">//3.首先我们要知道池子中你的自定义事件名称是否存在 </span></span><br><span class="line">        <span class="comment">// 如果存在了 我们就什么也不做 </span></span><br><span class="line">        <span class="comment">//如果不存在 我们就应该把这个名称添加进去 并且让它的值等于一个空数组 方便存放我的们事件处理函数</span></span><br><span class="line">        !pond.hasOwnProperty(type) ? pond[type] = [] :<span class="literal">null</span></span><br><span class="line">        <span class="comment">//4. 下一步 如果你这个自定义事件里 已经有我们的事件处理函数了 我们需要去重 如果不存在我们就需要添加</span></span><br><span class="line">        <span class="keyword">let</span> arr = pond[type]</span><br><span class="line">        <span class="comment">//判断 你的事件处理函数 在不在里面 如果在就去重 如果不在就添加</span></span><br><span class="line">        <span class="comment">// if(arr.includes(func)) return</span></span><br><span class="line">        <span class="keyword">for</span>(<span class="keyword">let</span> i = <span class="number">0</span>; i &lt; arr.length; i++)&#123;</span><br><span class="line">            <span class="keyword">if</span>(arr[i] === func)&#123;</span><br><span class="line">                <span class="keyword">return</span></span><br><span class="line">            &#125;</span><br><span class="line">        &#125;</span><br><span class="line">        arr.push(func)</span><br><span class="line">    &#125;</span><br><span class="line">    <span class="keyword">const</span> off = <span class="function"><span class="keyword">function</span> (<span class="params">type,func</span>)</span>&#123;</span><br><span class="line">        <span class="comment">//5.移除 </span></span><br><span class="line">        <span class="comment">// 如果 你穿进来的自定义名称 在我们的pond 里 那么我就开始移除你传过来的事件处理函数</span></span><br><span class="line">        <span class="comment">// 如果不在 我们就给一个空数组</span></span><br><span class="line">        <span class="keyword">let</span> arr = pond[type] || []</span><br><span class="line">        <span class="keyword">for</span>(<span class="keyword">let</span> i = <span class="number">0</span>; i &lt; arr.length; i++)&#123;</span><br><span class="line">            <span class="comment">// 找到相同的了 开始移除</span></span><br><span class="line">            <span class="keyword">if</span>(arr[i] === func)&#123;</span><br><span class="line">                arr.splice(i,<span class="number">1</span>)</span><br><span class="line">                <span class="comment">// 这里我们在添加的时候 就已经去重了 所以不会在重复了 这里我们就要把循环结束</span></span><br><span class="line">                <span class="keyword">break</span></span><br><span class="line">            &#125;</span><br><span class="line">        &#125;</span><br><span class="line">        <span class="comment">// 更快捷的方法 就是过滤</span></span><br><span class="line">        <span class="comment">//arr = arr.filter(item =&gt; item !== func)</span></span><br><span class="line">    &#125;</span><br><span class="line">    <span class="comment">//6.通知方法执行</span></span><br><span class="line">    <span class="keyword">const</span> fire = <span class="function"><span class="keyword">function</span> (<span class="params">type,...params</span>) </span>&#123;</span><br><span class="line">        <span class="comment">//这是找到了 你上面 要执行的函数</span></span><br><span class="line">        <span class="keyword">let</span> arr = pond[type] || []</span><br><span class="line">        arr = arr.slice(<span class="number">0</span>)</span><br><span class="line">        <span class="comment">// arr.forEach(item =&gt; item(...params))</span></span><br><span class="line">        <span class="keyword">for</span>(<span class="keyword">let</span> i = <span class="number">0</span>; i &lt; arr.length; i++)&#123;</span><br><span class="line">            <span class="comment">// 然后让每一个函数执行 并且 把参数传入进去</span></span><br><span class="line">            <span class="keyword">let</span> item = arr[i]</span><br><span class="line">            item(...params)</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line">    <span class="keyword">return</span> &#123;</span><br><span class="line">        on,</span><br><span class="line">        off,</span><br><span class="line">        fire</span><br><span class="line">    &#125;</span><br><span class="line">&#125;)()</span><br></pre></td></tr></table></figure>
<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">//以上我们就写完了 但是存在如下问题</span></span><br><span class="line"><span class="keyword">let</span> box = <span class="built_in">document</span>.getElementById(<span class="string">&#x27;box&#x27;</span>)</span><br><span class="line">box.onclick = <span class="function"><span class="keyword">function</span> (<span class="params">e</span>) </span>&#123;</span><br><span class="line">    subscribe.fire(<span class="string">&#x27;@aa&#x27;</span>,<span class="number">10</span>,<span class="number">20</span>,e)</span><br><span class="line">&#125;</span><br><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">fn1</span>(<span class="params">x,y,e</span>) </span>&#123;</span><br><span class="line">    <span class="built_in">console</span>.log(x,y,e)</span><br><span class="line">&#125;</span><br><span class="line">subscribe.on(<span class="string">&#x27;@aa&#x27;</span>,fn1)</span><br><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">fn2</span>(<span class="params"></span>)</span>&#123;</span><br><span class="line">    <span class="built_in">console</span>.log(<span class="number">2</span>)</span><br><span class="line">    <span class="comment">//这里 我们在触发fn2的时候 把fn1 和 fn2 删除</span></span><br><span class="line">    <span class="comment">//这里 我们第一次触发的的时候 fn1 和 fn2 应该还能触发</span></span><br><span class="line">    <span class="comment">// 但是 fn2 执行完毕之后 fn1 和 fn2 才会被删除</span></span><br><span class="line">    <span class="comment">// 但是 我们第一次触发的时候  fn1 和 fn2 fn5 还在 但是 fn3 和 fn4 却被删除了</span></span><br><span class="line">    <span class="comment">// 然后当我们点击第二次的时候 才恢复正常</span></span><br><span class="line">    subscribe.off(<span class="string">&#x27;@aa&#x27;</span>,fn1)</span><br><span class="line">    subscribe.off(<span class="string">&#x27;@aa&#x27;</span>,fn2)</span><br><span class="line">&#125;</span><br><span class="line">subscribe.on(<span class="string">&#x27;@aa&#x27;</span>,fn2)</span><br><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">fn3</span>(<span class="params"></span>)</span>&#123;</span><br><span class="line">    <span class="built_in">console</span>.log(<span class="number">3</span>)</span><br><span class="line">&#125;</span><br><span class="line">subscribe.on(<span class="string">&#x27;@aa&#x27;</span>,fn3)</span><br><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">fn4</span>(<span class="params"></span>)</span>&#123;</span><br><span class="line">    <span class="built_in">console</span>.log(<span class="number">4</span>)</span><br><span class="line">&#125;</span><br><span class="line">subscribe.on(<span class="string">&#x27;@aa&#x27;</span>,fn4)</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">fn5</span>(<span class="params"></span>)</span>&#123;</span><br><span class="line">    <span class="built_in">console</span>.log(<span class="number">5</span>)</span><br><span class="line">&#125;</span><br><span class="line">subscribe.on(<span class="string">&#x27;@aa&#x27;</span>,fn5)</span><br></pre></td></tr></table></figure>
<h2 id="数组塌陷"><a href="#数组塌陷" class="headerlink" title="数组塌陷"></a>数组塌陷</h2><figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line"><span class="number">1.</span> 我们在 fn2 函数里 在执行的时候 我们把 fn1 和 fn2 删除了</span><br><span class="line"><span class="number">2.</span> 所以我们第一次执行的时候 fn1 fn2 fn3 fn4 fn5 都应该被输出 第二次点击的时候 只输出 fn4 fn5 </span><br><span class="line"><span class="number">3.</span> 然后第一次执行的时候  删除了 fn3 fn4  而执行 fn1 fn2 fn5 </span><br><span class="line"><span class="number">4.</span> 第二次 执行的时候 才恢复正常 输出了 fn3 fn4 fn5 这种情况 叫数组塌陷</span><br><span class="line"><span class="number">5.</span> 数组塌陷 是 当我们 删除了数组中的某一些项 它后面的索引 会往前移</span><br></pre></td></tr></table></figure>
<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">const</span> off = <span class="function"><span class="keyword">function</span> (<span class="params">type,func</span>)</span>&#123;</span><br><span class="line">        <span class="keyword">let</span> arr = pond[type] || []</span><br><span class="line">        <span class="keyword">for</span>(<span class="keyword">let</span> i = <span class="number">0</span>; i &lt; arr.length; i++)&#123;</span><br><span class="line">            <span class="keyword">if</span>(arr[i] === func)&#123;</span><br><span class="line">                arr.splice(i,<span class="number">1</span>)</span><br><span class="line">                <span class="keyword">break</span></span><br><span class="line">            &#125;</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">fn2</span>(<span class="params"></span>)</span>&#123;</span><br><span class="line">    <span class="built_in">console</span>.log(<span class="number">2</span>)</span><br><span class="line">    subscribe.off(<span class="string">&#x27;@aa&#x27;</span>,fn1)</span><br><span class="line">    subscribe.off(<span class="string">&#x27;@aa&#x27;</span>,fn2)</span><br><span class="line">&#125;</span><br><span class="line"><span class="comment">//我们来理清循环顺序</span></span><br><span class="line">i = <span class="number">0</span> 的时候 我们执行 fn1</span><br><span class="line">i = <span class="number">1</span> 的时候 我们执行 fn2</span><br><span class="line">当我们执行 fn2 的时候 正常代码执行完毕 然后 我们开始 删除 fn1 和 fn2 </span><br><span class="line">原有的数组 </span><br><span class="line"><span class="comment">//索引       ---&gt;删除之后    //索引</span></span><br><span class="line">[<span class="number">0</span>,<span class="number">1</span>,<span class="number">2</span>,<span class="number">3</span>,<span class="number">4</span>]                [<span class="number">0</span>,<span class="number">1</span>,<span class="number">2</span>]</span><br><span class="line"><span class="comment">// 对应的元素 ---&gt;删除之后    //对应的元素</span></span><br><span class="line">[fn1,fn2,fn3,fn4,fn5]      [fn3,fn4,fn5]</span><br><span class="line"><span class="comment">//此时 i++</span></span><br><span class="line">i = <span class="number">2</span> 然后我们执行索引对应的元素 fn5 所以 fn3 fn4 没有执行</span><br><span class="line"><span class="comment">// 第二次 执行的就会恢复了</span></span><br></pre></td></tr></table></figure>
<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">// 我们通知的时候 可以把我们池子 克隆一份</span></span><br><span class="line"> <span class="comment">//6.通知方法执行</span></span><br><span class="line">    <span class="keyword">const</span> fire = <span class="function"><span class="keyword">function</span> (<span class="params">type,...params</span>) </span>&#123;</span><br><span class="line">        <span class="comment">//这是找到了 你上面 要执行的函数</span></span><br><span class="line">        <span class="keyword">let</span> arr = pond[type] || []</span><br><span class="line">        <span class="comment">//为了防止数组塌陷 我们克隆一份</span></span><br><span class="line">        arr.arr.slice(<span class="number">0</span>)</span><br><span class="line">        <span class="comment">// arr.forEach(item =&gt; item(...params))</span></span><br><span class="line">        <span class="keyword">for</span>(<span class="keyword">let</span> i = <span class="number">0</span>; i &lt; arr.length; i++)&#123;</span><br><span class="line">            <span class="comment">// 然后让每一个函数执行 并且 把参数传入进去</span></span><br><span class="line">            <span class="keyword">let</span> item = arr[i]</span><br><span class="line">            item(...params)</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br></pre></td></tr></table></figure>
<h2 id="基于工厂模式创建编写事件发布订阅"><a href="#基于工厂模式创建编写事件发布订阅" class="headerlink" title="基于工厂模式创建编写事件发布订阅"></a>基于工厂模式创建编写事件发布订阅</h2><figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line"><span class="number">1.</span> 工厂模式就是 我们的函数当作一个普通函数执行</span><br><span class="line"><span class="number">2.</span> 当普通函数执行的时候 也可以创造它的一个实例</span><br><span class="line"><span class="number">3.</span> jquery里面 大量的运用了这种思想</span><br></pre></td></tr></table></figure>
<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line"><span class="number">1.</span> 如何能让一个函数 当作一个普通函数执行 又能创建它的一个实例呢</span><br></pre></td></tr></table></figure>
<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">//1. 假如下面是我们的一个构造函数 我们希望它执行的时候 又能当作普通函数执行 又能创建它的一个实例</span></span><br><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">Sub</span> (<span class="params"></span>) </span>&#123;</span><br><span class="line">  <span class="comment">//6. 这样 当我们在调用 Sub() 的时候 我们其实是创建了init的一个实例 init的原型指向的却是 sub</span></span><br><span class="line">  <span class="keyword">return</span> <span class="keyword">new</span> init()</span><br><span class="line">&#125;</span><br><span class="line"><span class="comment">//2.下面我们在准备一个函数 用来创造 Sub的实例</span></span><br><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">init</span> (<span class="params"></span>) </span>&#123;</span><br><span class="line">  <span class="comment">// init 函数上的实例</span></span><br><span class="line">  <span class="built_in">this</span>.arr = []</span><br><span class="line">&#125;</span><br><span class="line"><span class="comment">//3. 我们在Sub 的原型上 写几个方法</span></span><br><span class="line">Sub.prototype = &#123;</span><br><span class="line">  <span class="title">constructor</span>:<span class="title">Sub</span></span><br><span class="line">  <span class="title">on</span>:<span class="title">function</span>(<span class="params"></span>)&#123;&#125;,</span><br><span class="line">  fire:<span class="function"><span class="keyword">function</span>(<span class="params"></span>)</span>&#123;&#125;,</span><br><span class="line">  off():&#123;&#125;</span><br><span class="line">&#125;</span><br><span class="line"><span class="comment">//4. 我们让我们init函数的原型 等于 我们 sub函数的原型</span></span><br><span class="line">init.prototype = Sub.prototype</span><br><span class="line"><span class="comment">//5. 这样我们在 new init() 的时候 init的实例__proto__ 就指向 我们sub 的原型 prototype</span></span><br></pre></td></tr></table></figure>
<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">//基于构造函数 模式 编写 发布订阅</span></span><br><span class="line">(<span class="function"><span class="keyword">function</span>(<span class="params"></span>)</span>&#123;</span><br><span class="line">    <span class="function"><span class="keyword">function</span> <span class="title">Sub</span> (<span class="params"></span>) </span>&#123;</span><br><span class="line">        <span class="keyword">return</span> <span class="keyword">new</span> init()</span><br><span class="line">    &#125;</span><br><span class="line">    <span class="function"><span class="keyword">function</span> <span class="title">init</span> (<span class="params"></span>) </span>&#123;</span><br><span class="line">        <span class="built_in">this</span>.pond = &#123;&#125;</span><br><span class="line">    &#125;</span><br><span class="line">    Sub.prototype = &#123;</span><br><span class="line">        <span class="title">constructor</span>:<span class="title">Sub</span>,</span><br><span class="line">        //发布的方法 就是向你的池子中添加方法</span><br><span class="line">        <span class="title">on</span>:<span class="title">function</span>(<span class="params">type,func</span>)&#123;</span><br><span class="line">            !<span class="built_in">this</span>.pond.hasOwnProperty(type)?<span class="built_in">this</span>.pond[type] = [] : <span class="literal">null</span></span><br><span class="line">            <span class="keyword">var</span> arr = <span class="built_in">this</span>.pond[type]</span><br><span class="line">            <span class="keyword">if</span>(arr.includes(func)) <span class="keyword">return</span></span><br><span class="line">            arr.push(func)</span><br><span class="line">        &#125;,</span><br><span class="line">        <span class="comment">// 通知的方法 从池子中执行方法</span></span><br><span class="line">        <span class="function"><span class="title">fire</span>(<span class="params">type,...params</span>)</span>&#123;</span><br><span class="line">            <span class="keyword">var</span> arr = <span class="built_in">this</span>.pond[type]</span><br><span class="line">            arr = arr.slice(<span class="number">0</span>)</span><br><span class="line">            <span class="keyword">for</span>(<span class="keyword">var</span> i = <span class="number">0</span>; i &lt; arr.length; i++)&#123;</span><br><span class="line">                <span class="keyword">var</span> item = arr[i]</span><br><span class="line">                item = item(...params)</span><br><span class="line">            &#125;</span><br><span class="line">        &#125;,</span><br><span class="line">        <span class="comment">// 移除池子中的方法</span></span><br><span class="line">        <span class="function"><span class="title">off</span>(<span class="params">type,func</span>)</span>&#123;</span><br><span class="line">            <span class="keyword">var</span> arr = <span class="built_in">this</span>.pond[type]</span><br><span class="line">            <span class="built_in">this</span>.pond[type] = arr.filter( <span class="function"><span class="params">item</span> =&gt;</span> &#123;</span><br><span class="line">                <span class="keyword">return</span> item !== func</span><br><span class="line">            &#125;)</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line">    init.prototype = Sub.prototype</span><br><span class="line">    <span class="built_in">window</span>.Sub = Sub</span><br><span class="line">&#125;)()</span><br></pre></td></tr></table></figure>
<figure class="highlight js"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line"><span class="number">1.</span> 命令式编程 每个步骤都自己来 优点 是 步骤可以把控 比如我们移除的时候使用的<span class="keyword">for</span>循环 就是每一步做什么 都由我们自己编写 比如找到对应的函数 自己去手动移除</span><br><span class="line"><span class="number">2.</span> 函数是编程 每个步骤 都不用自己做 只关注结果 比如我们移除的时候 写的第二个便利方法 filter 你只需告诉我你要移除哪项 就可以 优点是 低内聚高耦合 把功能代码给你封装好了</span><br><span class="line"><span class="number">3.</span> 地址 https:<span class="comment">//github.com/wazer1987/subscribe/blob/main/subscribe.js</span></span><br></pre></td></tr></table></figure>
</article><div class="post-copyright"><div class="post-copyright__title"><span class="post-copyright-info"><h>发布订阅</h></span></div><div class="post-copyright__type"><span class="post-copyright-info"><a href="http://example.com/2020/04/27/%E8%AE%BE%E8%AE%A1%E6%A8%A1%E5%BC%8F/">http://example.com/2020/04/27/%E8%AE%BE%E8%AE%A1%E6%A8%A1%E5%BC%8F/</a></span></div><div class="post-copyright-m"><div class="post-copyright-m-info"><div class="post-copyright-a"><h>作者</h><div class="post-copyright-cc-info"><h>北城韩雨</h></div></div><div class="post-copyright-c"><h>发布于</h><div class="post-copyright-cc-info"><h>2020-04-27</h></div></div><div class="post-copyright-u"><h>更新于</h><div class="post-copyright-cc-info"><h>2019-06-04</h></div></div><div class="post-copyright-c"><h>许可协议</h><div class="post-copyright-cc-info"><a class="icon" rel="noopener" target="_blank" title="Creative Commons" href="https://creativecommons.org/"><i class="fab fa-creative-commons"></i></a><a rel="noopener" target="_blank" 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<p style="background:rgba(255,255,255,1);margin:0"> <img src="/img/code.png"></img> </p></div></div><div class="sticky_layout"><div class="card-widget" id="card-toc"><div class="item-headline"><i class="fas fa-stream"></i><span>目录</span></div><div class="toc-content"><ol class="toc"><li class="toc-item toc-level-1"><a class="toc-link" href="#%E8%AE%BE%E8%AE%A1%E6%A8%A1%E5%BC%8F"><span class="toc-text">设计模式</span></a><ol class="toc-child"><li class="toc-item toc-level-2"><a class="toc-link" href="#%E5%8F%91%E5%B8%83%E8%AE%A2%E9%98%85%E8%AE%BE%E8%AE%A1%E6%A8%A1%E5%BC%8F"><span class="toc-text">发布订阅设计模式</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#DOM-0%E7%BA%A7"><span class="toc-text">DOM 0级</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#DOM-2%E7%BA%A7"><span class="toc-text">DOM 2级</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#%E4%BA%8B%E4%BB%B6%E6%B1%A0"><span class="toc-text">事件池</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#%E8%87%AA%E5%AE%9A%E4%B9%89%E4%BA%8B%E4%BB%B6%E6%B1%A0"><span class="toc-text">自定义事件池</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#%E5%9F%BA%E4%BA%8E%E5%8D%95%E5%88%A9%E6%A8%A1%E5%BC%8F%E7%BC%96%E5%86%99%E4%BA%8B%E4%BB%B6%E5%8F%91%E5%B8%83%E8%AE%A2%E9%98%85"><span class="toc-text">基于单利模式编写事件发布订阅</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#%E6%95%B0%E7%BB%84%E5%A1%8C%E9%99%B7"><span class="toc-text">数组塌陷</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#%E5%9F%BA%E4%BA%8E%E5%B7%A5%E5%8E%82%E6%A8%A1%E5%BC%8F%E5%88%9B%E5%BB%BA%E7%BC%96%E5%86%99%E4%BA%8B%E4%BB%B6%E5%8F%91%E5%B8%83%E8%AE%A2%E9%98%85"><span class="toc-text">基于工厂模式创建编写事件发布订阅</span></a></li></ol></li></ol></div></div><div class="card-widget card-recent-post"><div class="item-headline"><i class="fas fa-history"></i><span>最新文章</span></div><div class="aside-list"><div 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